Dolphin Cayman vs Dolphin Sigma

Introduction

Picking a robotic pool cleaner shouldn't feel like buying a car, but with the number of Dolphins on the market right now, I get why people freeze up. So let me make it simpler for two of them. I bought and tested the Dolphin Cayman and the Dolphin Sigma in my own pool, ran them both for months, and put them side by side on my channel. Both are genuinely good robots. They just chase different goals.

The Cayman is the one I'd hand a friend who wants to stop thinking about pool cleaning entirely. It has a weekly timer, it climbs walls, and the MaxBin is honestly one of the easier debris canisters I've dealt with. Smart Nav 2.0 and the HyperGrip tracks keep it moving in a sensible pattern instead of bouncing around at random, and in my testing that translated into a clean floor without a lot of missed passes.

The Sigma is a different animal. It's built on a commercial-grade platform, runs three motors, comes with a full app, and carries a three-year warranty instead of the shorter one. There's also a gyroscope inside it that makes a real difference in how it navigates. On paper that's a lot. In the pool, it mostly shows up as a robot that goes exactly where it means to.

After running both, here's the short version. The Cayman is the automation-and-value pick. The Sigma is the one you buy when you want the most advanced cleaner in the lineup and you're fine paying for it. If money were no object, the Sigma is the better machine, and the rest of this comparison walks through exactly why.

Below I'll break it down the same way I judge every robot: how it covers the pool, how it filters, and what its feature set and warranty actually get you. That's where these two separate.

How We Test

Every robot I write about lives in my pool for about three months before I'll say anything definitive about it. A slick first cleaning cycle tells you almost nothing. What tells you something is what happens after a dozen runs, once the tracks have worn in and the filter has been through a real season of leaves and pollen. So I run them, over and over, and watch three things: coverage, filtration, and the feature set plus warranty.

Coverage comes first. With the Cayman, I watched how it worked the floor and the walls and whether it left obvious gaps. It held up well. The Smart Nav 2.0 software and HyperGrip tracks kept it on a purposeful path, and the floor came out clean run after run without me nudging it into corners.

The Sigma pushed coverage further. Three motors and that commercial-grade platform give it more to work with, and the gyroscope is what really shows up in testing. It handles tight turns cleanly and holds a precise path, and it climbs to the waterline, which is usually the grimiest strip in the whole pool.

Filtration is next, and I test it the boring way: run the robot through real debris and cloudy water and see what the basket catches. The Cayman ships with a standard fine filter that handled everyday cleaning without complaint. When the water got murky or I was dealing with fine particles, swapping in the included NanoFilters made a clear difference. Pulling the Cayman's filters to rinse them is quick, which matters more than people expect.

The Sigma comes with both standard and ultrafine filters, and that pairing is the point. The ultrafine grabs the tiny stuff that keeps water looking hazy, and the oversize filter capacity meant I wasn't emptying it constantly even when it was picking up both big and fine debris.

Then there's the feature set and warranty, which is really a question of long-term value. The Cayman's weekly timer is the standout. Set it and the pool gets cleaned on schedule without you touching anything, and paired with a solid build that's a lot of convenience for the money.

The Sigma answers with its app. You can start it, schedule it, and control it from your phone, and it's backed by a three-year warranty rather than the shorter coverage. That longer warranty is a real signal about how the machine is built and how long Maytronics expects it to last.

After three months, both the Cayman and Sigma earned their keep in different ways. The Cayman wins on automation and ease of use. The Sigma wins on outright capability. Which one is right for you comes down to whether you want the simplest hands-off cleaner or the most complete one.

If you want to see how these two stack up against everything else I've tested, my best robotic pool cleaners of the year page keeps the full ranking updated.

Coverage

Coverage is where these two start to separate, so let's start here. The Cayman is strong on the floor and the walls. Smart Nav 2.0 and the HyperGrip tracks let it plan a path and stick to it, and in my pool it cleaned nearly everywhere it was supposed to.

Here's the catch: the Cayman doesn't clean the waterline. That's the one real gap, and if you're the kind of pool owner who watches oily scum build up right at the water's edge, you'll notice it. Everywhere else it does its job well, using the HyperBrush to scrub and lift debris off the floor and walls.

The Sigma covers more of the pool, full stop. The commercial-grade platform, three motors, and gyroscope give it the muscle and the smarts to work the floor, the walls, and the waterline, which is exactly where the grime tends to collect.

The gyroscope is doing quiet but important work here. It keeps the Sigma stable and holds its position while it scrubs the waterline, which is the strip most robots either skip or bump against and give up on. That single capability is a big part of why the Sigma feels like a more complete cleaner.

On scores, this is closer than it sounds. The Cayman earns a solid 10 for coverage, and I stand by that, but it's a 10 with an asterisk since it skips the waterline. The Sigma also earns a 10, and it gets there by cleaning the whole pool, waterline included. Same number, different completeness.

If waterline cleaning and precise navigation are what you care about, the Sigma is the clear pick. It holds its line and reaches the spots other robots dodge. But if you want a dependable, less expensive robot that does the floor and walls really well and you can live without the waterline, the Cayman is still a genuinely good machine.

Bottom line on coverage: both are excellent, but they suit different pools and different owners. The Cayman gives you excellent floor and wall cleaning with automation baked in, and the Sigma gives you the most complete coverage in the pair, waterline included.

For how these two compare to the rest of the field, check my best robotic pool cleaners of the year page, where I keep the full rundown current.

Filters

Filtration is one of those things people ignore until their water goes cloudy, so let's give it real attention. The Cayman uses a standard fine filter basket that pulls in everyday debris and keeps the water looking good. The part I like most is the MaxBin, which holds a lot and makes cleanup less of a chore.

The Sigma takes a different approach with both standard and ultrafine filters in the box. That combination is what lets it deal with regular debris and the fine particles that leave water looking hazy. The ultrafine filter is the one that grabs the microscopic stuff, and it's the reason the Sigma keeps water noticeably clearer.

Both robots do well, but the Sigma's dual filtration gives it the edge on water clarity. Being able to swap between standard and ultrafine means you can match the filter to whatever you're fighting that week, and that flexibility matters when conditions change.

That said, the Cayman's MaxBin earns its keep. It holds enough debris that you can stretch the time between empties, and if you're busy, that's a real, practical advantage you'll appreciate every week.

Maintenance is easy on both. The Cayman's MaxBin lifts out and cleans quickly, and the Sigma's filters are simple to handle too. The one small trade-off with the Sigma is that you have to decide which filter to run for the job, so there's a slight learning curve the Cayman doesn't have.

On the numbers, the Cayman lands a respectable 3.8 out of 5, earned by its solid standard fine filter and the convenience of the MaxBin. The Sigma pulls ahead at 4.7 out of 5, and the dual filtration is exactly why.

So if you want something powerful, simple, and low-fuss, the Cayman is a great call thanks to that big, easy MaxBin. If you want the more advanced filtration and the flexibility to chase clearer water, the Sigma is the winner.

For filtration specifically, the Sigma takes the category. Its dual system is more versatile and more effective, and it keeps water cleaner with less effort from you. For more head-to-heads like this, my best robotic pool cleaners of the year page has the rest.

Feature Set

Now the feature sets, because this is where the price gap starts to make sense. Both the Cayman and Sigma come loaded, but they're built around different owners.

The Cayman is all about hands-off automation. Its weekly timer lets you set a schedule and forget it, which is exactly what most people actually want from a robot. If you'd rather not think about your pool, this is the feature that sells it. On top of that, the Cayman runs a strong HyperBrush and the MaxBin, and that bigger debris capacity means fewer trips to empty it.

The Sigma adds more on top. It's built on a commercial-grade foundation and runs three motors, which gives it more cleaning power to spend. The gyroscope keeps it steady and precise so it can work tight corners and hold a clean path. And the app, with Wi-Fi, lets you control and schedule the whole thing from your phone instead of poking at buttons on the unit.

The other piece is the warranty. The Sigma carries a three-year warranty backed by Maytronics, which is longer than what a lot of robots offer and a fair signal of how it's built. Put the app, the three-motor power, and that warranty together and the Sigma sits at the top of the lineup.

On scores, the Cayman earns a strong 9.4 out of 10. The weekly timer and MaxBin make it easy to live with, and that's worth a lot. The Sigma takes a perfect 10 out of 10 here. Between the app, the gyroscope navigation, and the three-motor system, it delivers the most capable experience of the two.

So both bring real strengths. The Cayman is the fully automated, easy-to-live-with option for people who want minimal involvement. The Sigma is the pick for anyone who wants the most efficient, most complete cleaner out there. For how these two rank against everything else, my page on the best robotic pool cleaners of the year lays it all out.

Conclusion

So where does this leave you? Both the Cayman and the Sigma are excellent, but they're built for different people. The Cayman is about automation and convenience, and with an overall score of 9.4 it earns that reputation. The weekly timer, the strong wall cleaning, and the easy-going feature set make it the pick if you want pool cleaning to disappear from your to-do list.

The Sigma is the one to buy if you want the most complete, most advanced clean available. It scores 9.8 overall, and the gyroscope, three motors, and app all pull their weight. Add the NanoFilters and the three-year warranty and it's the stronger machine top to bottom.

Head to head, the Sigma wins on its advanced features and more complete cleaning. The Cayman is the better call if ease and automation are your priorities, but the Sigma's technology and broader coverage make it the standout here.

If neither of these is quite right, I've got other Dolphins worth a look. The Dolphin Premier is the one I'd grab for heavy leaf loads, the Dolphin Escape is the budget-friendly choice, and the Dolphin Quantum is a fantastic all-around performer. Each fits a different pool and budget.

For the full comparison against everything else I've tested, head to my best robotic pool cleaners of the year page, which I keep updated as new models come through.

Alternate Robots

The Cayman and Sigma are both strong, but they aren't your only options, and depending on your pool one of these might fit you better. Start with the Dolphin Premier. This one is my go-to for leaf-heavy pools thanks to its Multi-Media filtration and oversized leaf bag. If your pool sits under trees and you're constantly fishing out debris, the Premier is built for exactly that fight.

Next up is the Dolphin Quantum, which pairs strong cleaning with good filtration. It runs a larger XXL MaxBin so it holds more debris between empties, and the PowerJet 3D mobility system helps it reach the waterline and work tight corners. If you want one robot that does a bit of everything well, the Quantum is a great all-rounder.

And if you're watching your budget, look at the Aquabot REVA. It still cleans well, includes a gyroscope, and handles the waterline, so you're not giving up full coverage to save money. It doesn't have the Sigma's advanced feature list, but for the price it punches above its weight.

Want to see how all of these line up? My best robotic pool cleaners of the year page has the full ranking and my notes on each, so you can match a robot to your pool instead of guessing.